EU3 puts the player in charge of a European country with the task of guiding that country through centuries of development. The primary new feature in Heir to the Throne is called Casus Belli, a Latin phrase meaning “cause of war.” With Casus Belli, players can set up reasons for their country to go to war.

Other new features of the game include: peace treaties with more options; dynastic monarchies with arranged marriages and far-reaching effects on the game’s diplomacy model; new, powerful options for the Holy Roman Empire, including reformations enacted via imperial authority; special diplomatic options for merchant republics, including trade leagues; a Cultural Tradition function that improves advisors the same way Military Tradition improves generals and admirals; and more.

“Heir to the Throne gives Europa Universalis III players rich new options for strategically planning everything from succession of monarchs to the influence of cultural traditions on their nations. This new expansion pack brings an already excellent game even closer to replicating history’s richness,” said Virtual Programming CEO Mark Hinton in a statement.

The expansion requires the full version of EU3, and is priced at £14.95, €19.95, or US$19.95, depending on your market.